Recently, in order to solve exhaustion of frequency resources due to explosive increase of data communication, a need for using an unlicensed bandwidth such as TV whitespace (hereinafter, referred to as TVWS) has been gradually increased. Therefore, various attempts have been made to introduce a high-speed wireless data communication system such as a wireless local area network (WLAN) in a TVWS.
In a general radio frequency (RF) configuration of a wireless communication system (WLAN system), dynamic range of an RF front end is increased in proportion to an overall reception bandwidth.
In case of a TVWS, the RF front end requires frequency bandwidth wider than that of an existing wireless communication system. That is, in case of wireless communication using a TVWS, a dynamic range of the RF front end needs to be greater than the dynamic range of an existing wireless communication system.
In addition, even when a TVWS is divided into a plurality of subbands in consideration of a wideband property, the divided subband may be wider than that of an existing wireless communication system. Accordingly, in this case, an increased dynamic range is required for wireless communication.
In general, the dynamic range of the RF element is restricted by various factors such as implementation costs, element properties and power consumption. Such restriction in dynamic range increases unnecessary radiation to an adjacent frequency channel upon transmission and decreases a signal-to-noise ratio (SNR) due to a mutual modulation phenomenon generated by a signal of an adjacent channel upon reception.
Due to such a phenomenon, if the dynamic range is not increased upon communication using a TVWS, reception performance may deteriorate by unnecessary radiation occurring due to transmission of an adjacent channel.